1. Field of the Invention
The present invention relates to a touch panel which is (i) less prone to peeling-off of a transparent insulation film during handling operations or during storage in a rack and (ii) capable of reducing the number of times that a mechanism is stopped during storage in the rack using the mechanism.
2. Background of the Related Art
Conventionally, there are touch panels installed on the display screens of LCDs (liquid crystal displays) or CRTs (cathode-ray tubes) connected to computers for enabling a person to press thereon with a finger or a pen according to instructions displayed on the seen-through display screen for inputting the pressed positions within the display screen to the computer. Transparent-electrode type (resistance-film type) touch panels which are most common include two types of touch panels, which are digital (matrix) type touch panels that detect certain matrix-shaped coordinates and analog-type touch panels that detect arbitrary coordinates. These two types of touch panels are used for different applications, and, for example, digital type touch panels are used for menu inputting while analog type touch panels are used for inputting graphics and manually-written letters. Any of the digital type and analog type touch panels may have a film/glass structure or a film/film structure.
Referring to FIG. 13, a touch panel having a film/glass structure includes an upper electrode member 101 consisting of a transparent insulation film 111 and a transparent electrode on the lower surface thereof and a lower electrode member 102 consisting of a glass plate 121 and a transparent electrode on the upper surface thereof. The upper electrode member 101 and the lower electrode member 102 are attached to each other at their peripheral edges with cohesive agent or a double-sided tape 104. In the respective drawings, illustration of the transparent electrodes is omitted and the film materials and the glass material which are laminated are simply illustrated for ease of understanding.
Referring to FIG. 17, a touch panel having a film/film structure includes an upper electrode member 101 consisting of a transparent electrode on the lower surface of a transparent insulation film 111, a lower electrode member 102 consisting of a transparent electrode on the upper surface of a transparent insulation film 122, and a glass plate (transparent supporting plate) 105 adhered to the entire lower surface of the lower electrode member 102.
The aforementioned film/glass structure and film/film structure are disclosed in, for example, Japanese Patent No. 2587975 and Japanese Examined Utility Model Publication No. 3-37055.
However, the conventional touch panels include the transparent insulation film 111, 122 and the glass plates 121, 105 having end surfaces which are perpendicularly cut with respect to the surfaces of the respective members and, thus, have issues as follows.
(1) First, referring to FIG. 14, there is an issue that the transparent insulation film 111 is accidentally peeled off during handling operations of the touch panel, resulting in occurrences of defective products. When the touch panel is manually treated, the end surfaces of two parallel sides of the touch panel are sandwiched by fingers in order to prevent finger prints from being adhered to the inputting region, and it is difficult to always press the fingers 106 perpendicularly to the end surfaces. Particularly, larger-sized touch panels tend to cause the aforementioned issue. When a finger is obliquely pressed against an end surface of the transparent insulation film 111 of the touch panel, the upper portion of the end surface of the transparent insulation film is compressed and if the compression can not be further advanced any more, the lower portion of the end surface of the transparent insulation film 111 will be floated, namely peeled off.
Furthermore, if a finger is obliquely pressed against an end surface of the transparent insulation film of the touch panel during handling operations of the touch panel, causing the upper portion of the end surface of the transparent insulation film to be compressed, then the cohesive agent 104 may be compressed and thus extruded outwardly from between the upper electrode member 101 and the lower electrode member 102.
In the case of a double-sided tape, since a cohesive agent 104 is applied to the surface of a core material, the cohesive agent 104 of the double-sided tape may be similarly compressed and thus extruded outwardly from between the upper electrode member 101 and the lower electrode member 102. If the extruded cohesive agent 104 is adhered to the finger 106, the cohesive agent may be transferred to the surface or the back surface of the touch panel 108 when the finger 106 touches the touch panel subsequently.
Further, if the extruded cohesive agent 104 is adhered to a pressing tool for storing the touch panel 108 into a rack 7, as illustrated in FIG. 15, after the aforementioned handling operations, the adhered substance may be removed from the pressing tool and then may be transferred to the surface or the back surface of another touch panel 108 within the rack 7 during repeated storing using this pressing tool.
The cohesive agent being transferred to the surface or the back surface of the touch panel 108 will cause issues in terms of the following points.                Viewability        Inputting characteristics (when adhesive agent is adhered to the surface)        
The former issue of “viewability” is described in that adhered substances obstruct the see-through view to degrade the viewability of the display, since the touch panel is installed on a display device such as an LCD for enabling inputting while seeing through the display.
Further, the latter issue of “inputting characteristics” is described in that adhered substances degrade the smoothness of the inputting surface. Thus, degrading the writing comfort when the tip end of an inputting pen is slid along the touch panel surface for writing letters or the like using the inputting pen. Namely, the pen cannot move along the touch panel in a smooth manner, preventing accuracy of a desired input. This problem is a lethal blow to touch panels.
(2) Further, when the touch panel is transferred using a robot hand after the aforementioned handling operations, the extruded adhesive agent 104 may make it difficult to separate the chuck of the robot hand from the touch panel. In such cases, the touch panel is moved to a position different from the intended position. For example, the touch panel may fall onto a floor or the like, resulting in a fracture of the touch panel.
(3) Further, there has recently been a trend toward narrower peripheral edges of touch panels, requiring double-sided tape, etc., to have narrow widths. Therefore, if the extruded adhesive agent 104 is adhered to a finger 106, a pressing tool, or the like, the touch panel may be completely transferred to the finger 106, the pressing tool, or the like.
In such cases, the partition for attaching the upper electrode member 101 and the lower electrode member 102 of the touch panel to each other at their peripheral edges and for separating the inside (the air layer between the electrodes) of the touch panel from the outside of the touch panel is partially lost, causing the following issues.                Occurrences of Newton's rings        Operational malfunctions        
The “occurrences of Newton's rings” are described in that the air layer cannot generate repulsion forces against deformation of the upper electrode member 101 since the aforementioned partition-lost portion allows air to enter or exit, and as a result of repeated inputting, the upper electrode member 101 is sagged.
The latter issue of “operational malfunctions” includes two cases. The first case occurring where the aforementioned partition-lost portion allows moisture to enter the inside (the air layer between the electrodes) of the touch panel to degrade metal portions, causing operational malfunctions. Further, the second case occurring where the aforementioned partition-lost portion allows foreign substances to enter the inside (the air layer between the electrodes) of the touch panel to establish electrical conduction between the electrodes, causing operational malfunctions.
(4) Further, when the touch panel 108 is stored on the rack 7, there is an issue of peeling-off of the transparent insulation film 111. Storing of the touch panel 108 into respective stages of a rack 7 is performed by inserting the parallel two sides of the touch panel 108 in the depthwise direction along the horizontally-cut slots 7b on the inner sides of the side plates of the rack 7 (see FIG. 15), and the tip end portion of the touch panel 108 tends to contact with a shelf 7a of the rack 7 at each insertion opening of the rack 7 since the width of the slots 7b is narrow. Consequently, if the touch panel 108 is butted against a shelf 7a of the rack 7 at only an end surface of the transparent insulation film 111, the members below the transparent insulation film 111 will be inserted into the slot 7b of the rack 7 while the transparent insulation film 111 will be halted outside of the insertion opening, causing peeling-off thereof (see FIG. 16).
Furthermore, when the touch panels 108 are successively stored into respective stages of the rack 7 by a mechanism, even if an end surface of the transparent insulation film 111 is butted against a shelf 7a of the rack 7 at a single stage, the insertion cannot be further continued from then on or the mechanism can not be ready in time for the next insertion, causing the mechanism to be stopped.
These are issues specific to touch panels.
Therefore, it is an object of the present invention to provide touch panels which are less prone to peeling-off of transparent insulation films during handling operations or during storage in a rack, and are capable of reducing the number of times that the mechanism is stopped during storing into a rack with the mechanism, by overcoming the aforementioned issues.